1. Field of the Invention
The present invention relates to a novel method of producing a calcium silicate-based material.
2. Description of the Related Art
Calcium silicate is used in various applications, including not only pharmaceuticals and food additives, but also molding assistants and insulating materials. A known example of a typical production method of calcium silicate is a production method of calcium silicate or a calcium silicate-gypsum complex including a reaction step of mixing and reacting gypsum and an alkaline silicate in an aqueous medium, a washing step of washing a solid fraction obtained in the reaction step, a slurry step of converting the solid fraction obtained in the washing step to a slurry, a hydrothermal treatment step of carrying out hydrothermal treatment on the slurry solution obtained in the slurry step, and a separation step of separating the calcium silicate or calcium silicate-gypsum complex obtained in the hydrothermal treatment step (Japanese Patent Application Publication No. S56-5317). Other methods for producing calcium silicate according to various conditions have also been proposed (Japanese Patent Application publication Nos. S55-85445, S55-32753 and S54-93698).
Since calcium silicate produced by a method like that described above has particularly large bulk specific volume and oil absorption, it can be used, for example, as an additive for preventing adhesion or improving fluidity of dehumidifying agents, a carrier for impregnating a liquid substance and the like, a molding assistant or an adsorbent. In particular, calcium silicate has been proposed for used in the formulation of pharmaceuticals due to its specific aspect ratio and high oil absorption (Japanese Patent No. 4431391).
However, there is still room for improvement of conventional methods used to produce calcium silicate with respect to conditions of the hydrothermal synthesis reaction (and particularly, with respect to the temperature and duration thereof). Namely, although being able to synthesize calcium silicate in a shorter period of time and at a lower temperature would make it possible to contribute to production on an industrial scale, such technology has yet to be developed.